Video Lecture
Overview
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Terminology
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Source Code
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44 | # pylint: disable=too-few-public-methods
"Mediator Concept Sample Code"
class Mediator():
"The Mediator Concrete Class"
def __init__(self):
self.colleague1 = Colleague1()
self.colleague2 = Colleague2()
def colleague1_method(self):
"Calls the method provided by Colleague1"
return self.colleague1.method_1()
def colleague2_method(self):
"Calls the method provided by Colleague2"
return self.colleague2.method_2()
class Colleague1():
"This Colleague provides data for Colleague2"
@staticmethod
def method_1():
"A simple method"
return "Here is the Colleague1 specific data you asked for"
class Colleague2():
"This Colleague provides data for Colleague1"
@staticmethod
def method_2():
"A simple method"
return "Here is the Colleague2 specific data you asked for"
# The Client
MEDIATOR = Mediator()
# Colleague1 wants some data from Colleague2
DATA = MEDIATOR.colleague2_method()
print(f"COLLEAGUE1 <--> {DATA}")
# Colleague2 wants some data from Colleague1
DATA = MEDIATOR.colleague1_method()
print(f"COLLEAGUE2 <--> {DATA}")
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Output
| python ./mediator/mediator_concept.py
COLLEAGUE1 <--> Here is the Colleague2 specific data you asked for
COLLEAGUE2 <--> Here is the Colleague1 specific data you asked for
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Example Use Case
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Example UML Diagram
Source Code
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15 | "The Mediator Use Case Example"
from component import Component
from mediator import Mediator
MEDIATOR = Mediator()
COMPONENT1 = Component(MEDIATOR, "Component1")
COMPONENT2 = Component(MEDIATOR, "Component2")
COMPONENT3 = Component(MEDIATOR, "Component3")
MEDIATOR.add(COMPONENT1)
MEDIATOR.add(COMPONENT2)
MEDIATOR.add(COMPONENT3)
COMPONENT1.notify("data A")
COMPONENT2.notify("data B")
COMPONENT3.notify("data C")
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16 | "Each component stays synchronized through a mediator"
from interface_component import IComponent
class Component(IComponent):
"Each component stays synchronized through a mediator"
def __init__(self, mediator, name):
self._mediator = mediator
self._name = name
def notify(self, message):
print(self._name + ": >>> Out >>> : " + message)
self._mediator.notify(message, self)
def receive(self, message):
print(self._name + ": <<< In <<< : " + message)
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15 | "An interface that each component will implement"
from abc import ABCMeta, abstractmethod
class IComponent(metaclass=ABCMeta):
"An interface that each component will implement"
@staticmethod
@abstractmethod
def notify(message):
"The required notify method"
@staticmethod
@abstractmethod
def receive(message):
"The required receive method"
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18 | "The Subject that all components will stay synchronized with"
class Mediator():
"A Subject whose notify method is mediated"
def __init__(self):
self._components = set()
def add(self, component):
"Add components"
self._components.add(component)
def notify(self, message, originator):
"Add components except for the originator component"
for component in self._components:
if component != originator:
component.receive(message)
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Output
| python ./mediator/client.py
Component1: >>> Out >>> : data A
Component2: <<< In <<< : data A
Component3: <<< In <<< : data A
Component2: >>> Out >>> : data B
Component3: <<< In <<< : data B
Component1: <<< In <<< : data B
Component3: >>> Out >>> : data C
Component2: <<< In <<< : data C
Component1: <<< In <<< : data C
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Summary
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